Title:
Heating plate with planar heater zones for semiconductor processing
United States Patent 8546732


Abstract:
A heating plate for a substrate support assembly in a semiconductor plasma processing apparatus, comprises multiple independently controllable planar heater zones arranged in a scalable multiplexing layout, and electronics to independently control and power the planar heater zones. Each planar heater zone includes one or more heater elements made of an insulator-conductor composite. A substrate support assembly in which the heating plate is incorporated includes an electrostatic clamping electrode and a temperature controlled base plate. Methods for manufacturing the heating plate include bonding together ceramic sheets having planar heater zones, power supply lines, power return lines and vias.



Inventors:
Singh, Harmeet (Fremont, CA, US)
Application Number:
12/943492
Publication Date:
10/01/2013
Filing Date:
11/10/2010
Assignee:
Lam Research Corporation (Fremont, CA, US)
Primary Class:
Other Classes:
118/725, 118/728, 219/444.1, 219/539, 219/541
International Classes:
H05B3/26; F27B5/14; F27D11/02; H01L23/48; H01L23/52
View Patent Images:
US Patent References:
8222574Temperature measurement and control of wafer support in thermal processing chamber2012-07-17Sorabji et al.
8057602Apparatus and method for supporting, positioning and rotating a substrate in a processing chamber2011-11-15Koelmel et al.
7968825Temperature setting method of thermal processing plate, computer-readable recording medium recording program thereon, and temperature setting apparatus for thermal processing plate2011-06-28Jyousaka et al.
20110143462ADJUSTING SUBSTRATE TEMPERATURE TO IMPROVE CD UNIFORMITYJune, 2011Gaff et al.
7952049Method for multi-step temperature control of a substrate2011-05-31Tsukamoto
20110108706SEMICONDUCTOR DEVICE AND OPERATING METHOD THEREOF2011-05-12Koyama
7940064Method and apparatus for wafer level burn-in2011-05-10Segawa et al.
20110092072HEATING PLATE WITH PLANAR HEATING ZONES FOR SEMICONDUCTOR PROCESSING2011-04-21Singh et al.
7893387High rate method for stable temperature control of a substrate2011-02-22Ohata
20110033175ANNEALING APPARATUS2011-02-10Kasai et al.
20110005682Apparatus for Plasma Processing2011-01-13Savas et al.
20100283565Quench Propagation Circuit for Superconducting Magnets2010-11-11Blakes
20100257871Thin film thermoelectric devices for power conversion and cooling2010-10-14Venkatasubramanian et al.
7782583Electrostatic discharge protection device having low junction capacitance and operational voltage2010-08-24Moon
7718932Electrostatic chuck having radial temperature control capability2010-05-18Steger
20100116788Substrate temperature control by using liquid controlled multizone substrate support2010-05-13Singh et al.
20100078424TEMPERATURE CONTROLLED SUBSTRATE HOLDER WITH NON-UNIFORM INSULATION LAYER FOR A SUBSTRATE PROCESSING SYSTEM2010-04-01Tsukamoto et al.
20100055881HEAT TREATMENT METHOD FOR COMPOUND SEMICONDUCTOR AND APPARATUS THEREFOR2010-03-04Shimizu438/478
20090284894Electrostatic chuck2009-11-19Cooke
7586734Electrostatic chuck2009-09-08Kamitani et al.
20090215201METHOD FOR CONTROLLING SPATIAL TEMPERATURE DISTRIBUTION ACROSS A SEMICONDUCTOR WAFER2009-08-27Benjamin et al.
20090183677TEMPERATURE CONTROL DEVICE AND PROCESSING APPARATUS USING THE SAME2009-07-23Tian et al.
20090173445INDUCTIVELY COUPLED PLASMA PROCESSING APPARATUS HAVING INTERNAL LINEAR ANTENNA FOR LARGE ARE PROCESSING2009-07-09Yeom et al.
7504006Self-ionized and capacitively-coupled plasma for sputtering and resputtering2009-03-17Gopalraja et al.
20090031955VACUUM CHUCKING HEATER OF AXISYMMETRICAL AND UNIFORM THERMAL PROFILE2009-02-05Lu et al.118/728
7480129Detachable electrostatic chuck for supporting a substrate in a process chamber2009-01-20Brown et al.
7475551System employing temporal integration of thermoelectric action2009-01-13Ghoshal
20090000738ARRAYS OF INDUCTIVE ELEMENTS FOR MINIMIZING RADIAL NON-UNIFORMITY IN PLASMA2009-01-01Benjamin
20080202924Power Source Arrangement For Multiple-Target Sputtering System2008-08-28Bluck et al.
7417206Heater, wafer heating apparatus and method for manufacturing heater2008-08-26Nakamura219/444.1
7415312Process module tuning2008-08-19Barnett et al.219/444.1
7396431Plasma processing system for treating a substrate2008-07-08Chen et al.
7372001Ceramics heater2008-05-13Tachikawa et al.
20080092818THERMALLY ZONED SUBSTRATE HOLDER ASSEMBLY2008-04-24Fink et al.118/724
20080049374ELECTROSTATIC CHUCK WITH HEATER AND MANUFACTURING METHOD THEREOF2008-02-28Morioka et al.
20080029195Electrode Pattern For Resistance Heating Element and Wafer processing Apparatus2008-02-07Lu
7311782Apparatus for active temperature control of susceptors2007-12-25Strang et al.
7297894Method for multi-step temperature control of a substrate2007-11-20Tsukamoto
7279661Heating apparatus2007-10-09Okajima et al.
7275309Method of manufacturing electrical resistance heating element2007-10-02Matsuda et al.
7274004Method and apparatus for controlling the spatial temperature distribution across the surface of a workpiece support2007-09-25Benjamin et al.
7268322Semiconductor heating apparatus2007-09-11Kuibira et al.
7250309Integrated phase angle and optical critical dimension measurement metrology for feed forward and feedback process control2007-07-31Mak et al.
7230204Method and system for temperature control of a substrate2007-06-12Mitrovic et al.
20070125762Multi-zone resistive heater2007-06-07Cui et al.
7206184Vacuum plasma processor and method of operating same2007-04-17Ennis
7175714Electrode-built-in susceptor and a manufacturing method therefor2007-02-13Ootsuka et al.
7173222Aerosol generator having temperature controlled heating zone and method of use thereof2007-02-06Cox et al.
7141763Method and apparatus for rapid temperature change and control2006-11-28Moroz
20060226123Profile control using selective heating2006-10-12Birang
20060191637Etching Apparatus and Process with Thickness and Uniformity Control2006-08-31Zajac et al.
7075031Method of and structure for controlling electrode temperature2006-07-11Strang et al.
20060065367Plasma processing system for treating a substrate2006-03-30Chen et al.
6989210Fuel cartridge with thermo-degradable barrier system2006-01-24Gore
6985000Thermal control of a DUT using a thermal control substrate2006-01-10Feder
6979805Fuel-cell resistors and methods2005-12-27Arthur et al.
20050229854Method and apparatus for temperature change and control2005-10-20Moroz
20050215073Wafer supporting member2005-09-29Nakamura et al.
6921724Variable temperature processes for tunable electrostatic chuck2005-07-26Kamp et al.
6886347Workpiece chuck with temperature control assembly having spacers between layers providing clearance for thermoelectric modules2005-05-03Hudson et al.
6870728Electrolytic capacitor2005-03-22Burket et al.
20050016465Electrostatic chuck having electrode with rounded edge2005-01-27Ramaswamy et al.
6847014Method and apparatus for controlling the spatial temperature distribution across the surface of a workpiece support2005-01-25Benjamin et al.
6835290System and method for controlling thin film defects2004-12-28Reiter et al.
6825681Thermal control of a DUT using a thermal control substrate2004-11-30Feder et al.
6825617Semiconductor processing apparatus2004-11-30Kanno et al.
6815365Plasma etching apparatus and plasma etching method2004-11-09Masuda et al.
6795292Apparatus for regulating temperature of a process kit in a semiconductor wafer-processing chamber2004-09-21Grimard et al.
6746616Method and apparatus for providing etch uniformity using zoned temperature control2004-06-08Fulford et al.
6741446Vacuum plasma processor and method of operating same2004-05-25Ennis
6740853Multi-zone resistance heater2004-05-25Johnson et al.
6739138Thermoelectric modules and a heating and cooling apparatus incorporating same2004-05-25Saunders et al.
6664515Circuit pattern of resistance heating elements and substrate-treating apparatus incorporating the pattern2003-12-16Natsuhara et al.
6612673System and method for predicting dynamic thermal conditions of an inkjet printing system2003-09-02Giere et al.
6566632Hot plate and semiconductor device manufacturing method using the same2003-05-20Katata et al.
6523493Ring-shaped high-density plasma source and method2003-02-25Brcka
6512207Apparatus and method for the treatment of substrates2003-01-28Dress et al.
20020185488Circuit pattern of resistance heating elements and substrate-treating apparatus incorporating the pattern2002-12-12Natsuhara et al.
6483690Ceramic electrostatic chuck assembly and method of making2002-11-19Nakajima et al.
6475336Electrostatically clamped edge ring for plasma processing2002-11-05Hubacek
20020159216Vacuum plasma processor and method of operating same2002-10-31Ennis
6469283Method and apparatus for reducing thermal gradients within a substrate support2002-10-22Burkhart et al.219/444.1
6403403Diode isolated thin film fuel cell array addressing method2002-06-11Mayer et al.
20020043528Ceramic heater2002-04-18Ito
6353209Temperature processing module2002-03-05Schaper et al.
6271459Heat management in wafer processing equipment using thermoelectric device2001-08-07Yoo
6222161Heat treatment apparatus2001-04-24Shirakawa et al.
6175175Levitation pressure and friction losses in superconducting bearings2001-01-16Hull
6169275Ceramic heater and oxygen sensor using the same2001-01-02Noda et al.
6100506Hot plate with in situ surface temperature adjustment2000-08-08Colelli, Jr. et al.
6095084High density plasma process chamber2000-08-01Shamouilian et al.
6060697Substrate processing apparatus having regulated power consumption and method therefor2000-05-09Morita et al.
5886866Electrostatic chuck having a combination electrode structure for substrate chucking, heating and biasing1999-03-23Hausmann
5851298Susceptor structure for mounting processing object thereon1998-12-22Ishii
5802856Multizone bake/chill thermal cycling module1998-09-08Schaper et al.
5740016Solid state temperature controlled substrate holder1998-04-14Dhindsa
5667622In-situ wafer temperature control apparatus for single wafer tools1997-09-16Hasegawa et al.
5665166Plasma processing apparatus1997-09-09Deguchi et al.
5635093Heating plate for heating an object placed on its surface and chemical treatment reactor equipped with said plate1997-06-03Arena et al.
5536918Heat treatment apparatus utilizing flat heating elements for treating semiconductor wafers1996-07-16Ohkase et al.
5515683Thermoelectric heating or cooling device1996-05-14Kessler
5504471Passively-multiplexed resistor array1996-04-02Lund
5414245Thermal-ink heater array using rectifying material1995-05-09Hackleman
5255520Advanced thermoelectric heating and cooling system1993-10-26O'Geary et al.
5059770Multi-zone planar heater assembly and method of operation1991-10-22Mahawili
3440883ELECTRONIC SEMICONDUCTOR THERMOMETER1969-04-29Lightner



Foreign References:
JP2005123286May, 2005SUBSTRATE TREATMENT EQUIPMENT
JP2005294237October, 2005PLANAR HEATER
KR20080058109June, 2008
Other References:
Commonly-Owned U.S. Utility U.S. Appl. No. 12/582,991, filed Oct. 21, 2009.
Commonly-Owned U.S. Utility U.S. Appl. No. 12/910,347, filed Oct. 22, 2010.
Commonly-Owned U.S. Utility U.S. Appl. No. 13/234,473, filed Sep. 16, 2011.
Commonly-Owned U.S. Utility U.S. Appl. No. 13/237,444, filed Sep. 20, 2011.
Commonly-Owned U.S. Utility U.S. Appl. No. 13/238,396, filed Sep. 21, 2011.
Ayars, Eric, “Bandgap in a Semiconductor Diode”, Advanced and Intermediate Instructional Labs Workshop, AAPT Summer Meeting, California State University, Chicago, Jul. 20, 2008 http://phys.csuchico.edu/-eayars/publications/bandgap.pdf.
International Search Report and Written Opinion mailed Feb. 22, 2012 for PCT/US2011/058590.
Primary Examiner:
Pelham, Joseph M.
Attorney, Agent or Firm:
Buchanan Ingersoll & Rooney PC
Claims:
I claim:

1. A heating plate for a substrate support assembly used to support a semiconductor substrate in a semiconductor processing apparatus, the heating plate comprising: an electrically insulating layer; planar heater zones comprising at least first, second, third and fourth planar heater zones, each comprising one or more heater element made of an insulator-conductor composite, the planar heater zones laterally distributed across the electrically insulating layer and operable to tune a spatial temperature profile on the semiconductor substrate; power supply lines comprising at least a first electrically conductive power supply line electrically connected to the first and second planar heater zones and a second electrically conductive power supply line electrically connected to the third and fourth planar heater zones; power return lines comprising at least a first electrically conductive power return line electrically connected to the first and third planar heater zones and a second electrically conductive power return line electrically connected to the second and fourth planar heater zones.

2. The heating plate of claim 1, wherein the insulator-conductor composite comprises one or more insulator selected from the group consisting of Al2O3, SiO2, Si3N4, AlN and a mixture thereof, and one or more conductor selected from the group consisting of Al, Cu, Mo, W, Au, Ag, Pt, Pd, C, MoSi2, WC, SiC and a mixture thereof.

3. The heating plate of claim 2, wherein the insulator-conductor composite comprises up to 30 wt % of Al2O3 and balance of W.

4. The heating plate of claim 1, wherein the planar heater zones are sized such that: (a) each planar heater zone is 0.1 to 1 cm2, or (b) each planar heater zone is 2 to 3 cm2, or (c) each planar heater zone is 1 to 15 cm2, or (d) each planar heater zone is 16 to 100 cm2.

5. The heating plate of claim 1, wherein the heating plate includes 100 to 400 planar heater zones.

6. The heating plate of claim 1, wherein the electrically insulating layer comprises a polymer material, a ceramic material, a fiberglass composite, or a combination thereof.

7. The heating plate of claim 1, wherein the total number of the power supply lines and the power return lines is equal to or less than the total number of the planar heater zones.

8. The heating plate of claim 1, wherein a total area of the planar heater zones is from 50% to 99% of an upper surface of the heating plate.

9. The heating plate of claim 1, wherein the planar heater zones are arranged in a rectangular grid; and the planar heater zones are separated from each other by gaps at least 1 millimeter in width and at most 10 millimeters in width.

10. A substrate support assembly comprising: an electrostatic chuck (ESC) including at least one electrostatic clamping electrode configured to electrostatically clamp a semiconductor substrate on the substrate support assembly; the heating plate of claim 1; and a cooling plate attached to a lower side of the heating plate by a thermal barrier layer.

11. The substrate support assembly of claim 10, further comprising at least one primary heater layer arranged above or below and the planar heater zones of the heating plate, wherein the primary heater layer is electrically insulated from the planar heater zones, the power supply lines, and the power return lines of the heating plate; the primary heater layer includes at least one heater which provides mean temperature control of the semiconductor substrate; the planar heater zones provide radial and azimuthal temperature profile control of the semiconductor substrate, during processing thereof.

12. The substrate support assembly of claim 11, wherein the primary heater layer includes two or more heaters.

Description:

BACKGROUND

With each successive semiconductor technology generation, substrate diameters tend to increase and transistor sizes decrease, resulting in the need for an ever higher degree of accuracy and repeatability in substrate processing. Semiconductor substrate materials, such as silicon substrates, are processed by techniques which include the use of vacuum chambers. These techniques include non plasma applications such as electron beam deposition, as well as plasma applications, such as sputter deposition, plasma-enhanced chemical vapor deposition (PECVD), resist strip, and plasma etch.

Plasma processing systems available today are among those semiconductor fabrication tools which are subject to an increasing need for improved accuracy and repeatability. One metric for plasma processing systems is increased uniformity, which includes uniformity of process results on a semiconductor substrate surface as well as uniformity of process results of a succession of substrates processed with nominally the same input parameters. Continuous improvement of on-substrate uniformity is desirable. Among other things, this calls for plasma chambers with improved uniformity, consistency and self diagnostics.

SUMMARY

Described herein is a heating plate for a substrate support assembly used to support a semiconductor substrate in a semiconductor processing apparatus, the heating plate comprising: an electrically insulating layer; planar heater zones comprising at least first, second, third and fourth planar heater zones, each comprising one or more heater elements made of an insulator-conductor composite, the planar heater zones laterally distributed across the electrically insulating layer and operable to tune a spatial temperature profile on the semiconductor substrate; power supply lines comprising at least a first electrically conductive power supply line electrically connected to the first and second planar heater zones and a second electrically conductive power supply line electrically connected to the third and fourth planar heater zones; power return lines comprising at least a first electrically conductive power return line electrically connected to the first and third planar heater zones and a second electrically conductive power return line electrically connected to the second and fourth planar heater zones.

BRIEF DESCRIPTION OF FIGURES

FIG. 1 is a schematic cross-sectional view of a substrate support assembly in which a heating plate with an array of planar heater zones is incorporated, the substrate support assembly also comprising an electrostatic chuck (ESC).

FIG. 2 illustrates the electrical connection of power supply lines and power return lines to an array of planar heater zones in a heating plate which can be incorporated in a substrate support assembly.

FIG. 3 is a schematic cross-sectional view of a substrate support assembly in which a heating plate is incorporated, the substrate support assembly further including a primary heater layer.

FIG. 4 is a schematic of an exemplary plasma processing chamber, which can include a substrate support assembly with the heating plate described herein.

DETAILED DESCRIPTION

Radial and azimuthal substrate temperature control in a semiconductor processing apparatus to achieve desired critical dimension (CD) uniformity on the substrate is becoming more demanding. Even a small variation of temperature may affect CD to an unacceptable degree, especially as CD approaches sub-100 nm in semiconductor fabrication processes.

A substrate support assembly may be configured for a variety of functions during processing, such as supporting the substrate, tuning the substrate temperature, and supplying radio frequency power. The substrate support assembly can comprise an electrostatic chuck (ESC) useful for electrostatically clamping a substrate onto the substrate support assembly during processing. The ESC may be a tunable ESC (T-ESC). A T-ESC is described in commonly assigned U.S. Pat. Nos. 6,847,014 and 6,921,724, which are hereby incorporated by reference. The substrate support assembly may comprise a ceramic substrate holder, a fluid-cooled heat sink (hereafter referred to as cooling plate) and a plurality of concentric planar heater zones to realize step by step and radial temperature control. Typically, the cooling plate is maintained between −20° C. and 80° C. The heaters are located on the cooling plate with a layer of thermal insulator in between. The heaters can maintain the support surface of the substrate support assembly at temperatures about 0° C. to 90° C. above the cooling plate temperature. By changing the heater power within the plurality of planar heater zones, the substrate support temperature profile can be changed. Further, the mean substrate support temperature can be changed step by step within the operating range of 0 to 90° C. above the cooling plate temperature. A small azimuthal temperature variation poses increasingly greater challenges as CD decreases with the advance of semiconductor technology.

Controlling temperature is not an easy task for several reasons. First, many factors can affect heat transfer, such as the locations of heat sources and heat sinks, the movement, materials and shapes of the media. Second, heat transfer is a dynamic process. Unless the system in question is in heat equilibrium, heat transfer will occur and the temperature profile and heat transfer will change with time. Third, non-equilibrium phenomena, such as plasma, which of course is always present in plasma processing, make theoretical prediction of the heat transfer behavior of any practical plasma processing apparatus very difficult if not impossible.

The substrate temperature profile in a plasma processing apparatus is affected by many factors, such as the plasma density profile, the RF power profile and the detailed structure of the various heating the cooling elements in the chuck, hence the substrate temperature profile is often not uniform and difficult to control with a small number of heating or cooling elements. This deficiency translates to non-uniformity in the processing rate across the whole substrate and non-uniformity in the critical dimension of the device dies on the substrate.

In light of the complex nature of temperature control, it would be advantageous to incorporate multiple independently controllable planar heater zones in the substrate support assembly to enable the apparatus to actively create and maintain the desired spatial and temporal temperature profile, and to compensate for other adverse factors that affect CD uniformity.

Described herein is a heating plate for a substrate support assembly in a semiconductor processing apparatus, wherein the heating plate has multiple independently controllable planar heater zones that include heater elements made from a conductor-insulator composite. This heating plate comprises a scalable multiplexing layout scheme of the planar heater zones, power supply lines and power return lines (collectively, power lines). By tuning the power of the planar heater zones, the temperature profile during processing can be shaped both radially and azimuthally. More details are disclosed in commonly-owned U.S. patent application Ser. No. 12/582,991, the disclosure of which is hereby incorporated by reference. Although this heating plate is primarily described for a plasma processing apparatus, this heating plate can also be used in other semiconductor processing apparatuses that do not use plasma.

The planar heater zones in this heating plate are preferably arranged in a defined pattern, for example, a rectangular grid, a hexagonal grid, a polar array, concentric rings or any desired pattern. Each planar heater zone may be of any suitable size and may have one or more heater elements. When a planar heater zone is powered, all heater elements therein are powered; when a planar heater zone is not powered, all heater elements therein are not powered. To minimize the number of electrical connections, power supply lines and power return lines are arranged such that each power supply line is connected to a different group of planar heater zones and each power return line is connected to a different group of planar heater zones, each planar heater zone being in one of the groups connected to a particular power supply line and one of the groups connected to a particular power return line. No two planar heater zones are connected to the same pair of power supply and power return lines. A planar heater zone can be activated by directing electrical current through a pair of power supply line and power return line to which this particular planar heater zone is connected. The power density of the heater elements is preferably less than 10 W/cm2, more preferably less than 5 W/cm2. In one embodiment, each planar heater zone is not larger than four device dies being manufactured on a semiconductor substrate, or not larger than two device dies being manufactured on a semiconductor substrate, or not larger than one device die being manufactured on a semiconductor substrate, or 16 to 100 cm2, or 1 to 15 cm2, or 2 to 3 cm2, or 0.1 to 1 cm2 in area to correspond to the device dies on the substrate. The heating plate can include any suitable number of planar heater zones, such as 100 to 1000 planar heater zones. The thickness of the heater elements may range from 2 micrometers to 1 millimeter, preferably 5-80 micrometers. To allow space between planar heater zones and/or power supply and power return lines, the total area of the planar heater zones may be up to 99% of the area of the upper surface of the substrate support assembly, e.g. 50-99% of the area. The power supply lines or the power return lines may be arranged in gaps ranging from 1 to 10 mm between the planar heater zones, or in separate planes separated from the planar heater zones plane by electrically insulating layers. The power supply lines and the power return lines are preferably made as wide as the space allows, in order to carry large current and reduce Joule heating. In one embodiment, in which the power lines are in the same plane as the planar heater zones, the width of the power lines is preferably between 0.3 mm and 2 mm. In another embodiment, in which the power lines are on different planes than the planar heater zones, the width of the power lines can be as large as the planar heater zones, e.g. for a 300 mm chuck, the width can be 1 to 2 inches. Preferably, the materials of the power supply lines and power return lines are materials with low resistivity, such as Cu, Al, W, Inconel® or Mo.

A conventional resistive heater element typically comprises a serpentine trace made of electrical conductors with low resistivity, such as Al, Cu, W, Inconel® and Mo. Under a fixed input voltage V, the heating power P of the resistive heater element is V2/R, wherein R is the electrical resistance thereof. R can be expressed as (ρ·L)/(W·T), wherein ρ is the electrical resistivity of the material the serpentine trace is made of; L, W and T are the total trace length (i.e. the length measured by following the serpentine trace), width and thickness of the serpentine trace, respectively. Geometrical factors L, W and T of the serpentine trace are constrained by the physical size of the planar heater zone in which the resistive heater element is enclosed. L has an upper limit due to available area in the planar heater zone; Wand T have a lower limit due to fabrication techniques. Thus, R has an upper limit and P has a lower limit. It is increasingly difficult to meet the power density requirement (preferably less than 10 W/cm2, more preferably less than 5 W/cm2. Increasing the electrical resistivity ρ, as described hereinbelow, can alleviate this problem.

FIG. 1 shows a substrate support assembly comprising one embodiment of the heating plate having an electrically insulating layer 103. The layer 103 may have one or more layers made of a polymer material, an inorganic material, a ceramic such as silicon oxide, alumina, yttria, aluminum nitride or other suitable material. The substrate support assembly further comprises (a) at least one ESC (electrostatic clamping) electrode 102 (e.g. monopolar or bipolar) embedded in the layer 103 to electrostatically clamp a substrate to the surface of the layer 103 with a DC voltage, (b) a thermal barrier layer 107, (c) a cooling plate 105 containing channels 106 for coolant flow. The power supply lines and power return lines are not shown for clarity.

As shown in FIG. 2, each of the planar heater zones 101 is connected to one of the power supply lines 201 and one of the power return lines 202. No two planar heater zones 101 share the same pair of power supply 201 and power return 202 lines. By suitable electrical switching arrangements, it is possible to connect a pair of power supply line 201 and power return line 202 to a power supply (not shown), whereby only the planar heater zone connected to this pair of power lines is powered. The time-averaged heating power of each planar heater zone can be individually tuned by time-domain multiplexing. In order to prevent crosstalk between different heater zones, a rectifier 250 (e.g. a diode) may be serially connected between each heater zone and the power supply lines connected thereto (as shown in FIG. 2), or between each heater zone and the power return lines connected thereto (not shown). The rectifier can be physically located in the heating plate or any suitable location. Alternatively, any current blocking arrangement such as solid state switches can be used to prevent crosstalk.

Each planar heater zone 101 comprises at least one heater element made of an insulator-conductor composite. In one embodiment, the insulator-conductor composite comprises one or more insulator materials selected from the group consisting of Al2O3, SiO2, Y2O3, Si3N4, AlN, and one or more conductor materials selected from the group consisting of Al, Cu, Mo, W, Au, Ag, Pt, Pd, C, MoSi2, WC, SiC. The insulator-conductor composite can be made by mixing powders (preferably having particle sizes from 0.2 to 20 microns) of an insulator and a conductor with a suitable liquid (e.g. methanol, ethanol, acetone, isopropyl alcohol, water, mineral oil, or a mixture thereof) into a slurry, screen printing the slurry and sintering the slurry. In a preferred embodiment, the insulator-conductor composite comprises up to 30 wt % of Al2O3 and balance of W.

The layer 103 of the heating plate is preferably made of ceramic. The heating plate can be made by an exemplary method comprising: pressing a mixture of ceramic powder, binder and liquid into sheets; drying the sheets; forming vias in the sheets by punching holes in the sheets; forming power supply lines and power return lines on the sheets by screen printing a slurry of conducting powder (e.g. W, WC, doped SiC or MoSi2), pressing a precut metal foil, spraying a slurry of conducting powder, or any other suitable technique; forming heater elements by screen printing or spraying a slurry of insulator and conductor powders; aligning the sheets; bonding the sheets together by sintering to form the layer 103; filling the vias with a slurry of conducting powder. The sheets can be about 0.3 mm in thickness.

FIG. 3 shows the substrate support assembly of FIG. 1, further comprising the primary heater layer 601. Preferably, the primary heater layer 601 includes at least two individually controlled high-power heaters. The power of the primary heaters is between 100 and 10000 W, preferably, between 1000 and 5000 W. The primary heaters may be arranged as a rectangular grid, concentric annular zones, radial zone or combination of annular zones and radial zones. The primary heaters may be used for changing the mean temperature, tuning the radial temperature profile, or step-by-step temperature control on the substrate. The primary heaters are above thermal barrier layer 107 and may be located above or below the heater zones 101.

As an overview of how a plasma processing chamber operates, FIG. 4 shows a schematic of a plasma processing chamber comprising a chamber 713 in which an upper showerhead electrode 703 and a substrate support assembly 704 are disposed. A substrate 712 is loaded through a loading port 711 onto the substrate support assembly 704. A gas line 709 supplies process gas to the upper showerhead electrode 703 which delivers the process gas into the chamber. A gas source 708 (e.g. a mass flow controller supplying a suitable gas mixture) is connected to the gas line 709. A RF power source 702 is connected to the upper showerhead electrode 703. In operation, the chamber is evacuated by a vacuum pump 710 and the RF power is capacitively coupled between the upper showerhead electrode 703 and a lower electrode in the substrate support assembly 704 to energize the process gas into a plasma in the space between the substrate 712 and the upper showerhead electrode 703. The plasma can be used to etch device die features into layers on the substrate 712. The substrate support assembly 704 includes a heating plate as described herein. As described above, it should be appreciated that while the detailed design of the plasma processing chamber may vary, RF power is coupled to the plasma through the substrate support assembly 704.

Examples of suitable insulating and conductive material for use in manufacture of the substrate support assembly are disclosed in commonly assigned U.S. Pat. No. 6,483,690, the disclosure of which is hereby incorporated by reference.

While a heating plate, methods of manufacturing the heating plate, and a substrate support assembly comprising the heating plate have been described in detail with reference to specific embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications can be made, and equivalents employed, without departing from the scope of the appended claims.